Tape can soften a drum hit, thicken a bass line, roughen a synth, or let a loop wander in pitch. Saturation, filtering, hiss, and movement are all part of the sound. The settings determine how much of each you hear.
You can get tape-like sounds from a drive, a few filters, some noise, and a pitch modulator. Those are useful tools. I built Tape around the recording process itself: audio drives a record head, moving magnetic material holds the recording, and a separate playback head reads it. The sound comes from calculating what happens along that path. Changing the material, the heads, or the speed changes how the recording behaves.
There are filters in the electronics, and there is a tanh function that rounds off the record amplifier’s current. The magnetic material also has memory. Its response depends on the sequence of fields it has experienced, and it can stay magnetized after the field disappears. This is hysteresis, and it is what allows the modeled tape to hold a recording.
Turn up the recording level and the peaks start to round off. Drums can feel denser, a bass note can gain extra harmonics, and a synth can move from a little thickness into obvious breakup. Both the amplifier’s current limit and the material’s saturation contribute. This is compression through saturation; there are no compressor attack and release settings. Depending on the setup, pushing harder can make things quite abrasive.
The tonal changes depend on the recording too. Treble occupies shorter patterns along the tape, and the head has a harder time resolving them. Slower tape makes those patterns shorter still. Head gap, contact, coating depth, and the electronics all affect what gets through. You can hear a snare lose some crack or a cymbal lose its edge while the lower part of the sound stays more present.
Bias is a useful place to explore. It is a rapid alternating current at the record head that works the magnetic material alongside the music. Too little can make quiet notes rough or buzzy. Increasing it can smooth the response; going further can reduce recording level and treble. The useful range changes with the material and head geometry. A small bias change can therefore alter the texture as well as the brightness.
Wow and flutter come from variations in tape speed. Slow movement makes held notes wander; faster movement adds an unsteady edge. Changing contact with the playback head can make brightness and level move too. These can be subtle on a busy drum loop and much easier to hear on a held chord.
The noise has a few sources. The model gives the material fixed magnetic irregularities and adds noise in the playback electronics. Some material variation grows with the recording, adding grain around notes. Speed and playback filtering shape what you hear. The cleaner settings keep these contributions small; worn settings bring them forward.
With feedback and recording enabled, the returning sound goes through the recording process again. Repeats can lose detail, build up distortion, and carry noise into later passes. There is an approximation here: the loop stores reproduced audio between passes, rather than keeping every piece of tape’s microscopic magnetic history around the whole loop. Playback-only mode reads that saved waveform, and erasure attenuates it. The magnetic recording and pickup calculations happen when recording is active.
Physical modeling gives these controls a shared cause. Turning the bias or changing the head gap can affect several parts of the sound at once. It is still a simplified digital simulation, and the presets are virtual machines rather than calibrated copies of particular decks. You can make similar sounds with other tools. The interesting part here is being able to explore the recording process through its physical parameters.
Try a drum loop and a held note with feedback down first. Change the recording level, then bias, then speed, adjusting the output so louder does not automatically win. Once you like the first pass, bring the feedback up and hear what survives. The control guide explains the settings, and How it works follows the magnetic recording in more detail.